package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    @Autowired
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
         Shop shop = queryWithMutex(id);

//        //逻辑过期解决缓存击穿
//        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY,id, Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.SECONDS);

        if(shop == null){
            return Result.fail("店铺不存在！");
        }

        //7.返回
        return Result.ok(shop);
    }

    private static final ExecutorService CACHE_BUILD_EXECUTOR= Executors.newFixedThreadPool(10);

    public Shop queryWithLogicalExpire(Long id){
        String key=CACHE_SHOP_KEY+ id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY+ id);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.存在，直接返回
            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();

        //5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1未过期，直接返回店铺信息
            return shop;
        }
        //5.2已过期，需要进行缓存重建

        //6.缓存重建
        //6.1.获取互斥锁
        String lockKey=LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //6.2.判断是否获取锁成功
        if(isLock){
            //6.3.成功，开启独立线程，实现缓存重建
            CACHE_BUILD_EXECUTOR.submit(()->{
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unlock(lockKey);
                }
            });
        }
        //6.4.返回过期的店铺信息
        return shop;
    }

    //互斥锁解决缓存击穿
    public Shop queryWithMutex(Long id){
        String key=CACHE_SHOP_KEY+ id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY+ id);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson!=null){
            //返回一个错误信息
            return null;
        }
        //4.实现缓存重建
        //4.1获取互斥锁
        String locKey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(locKey);
            //4.2判断是否成功
            if(!isLock){
                //4.3失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4成功，根据id查询数据库
            shop = getById(id);
            //模拟重建延迟
            Thread.sleep(200);
            //5.不存在，返回错误
            if (shop == null) {
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+ id,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+ id, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //7.释放互斥锁
            unlock(locKey);
        }

        //8.返回
        return shop;
    }

    //缓存击穿
    public Shop queryWithPassThrough(Long id){
        String key=CACHE_SHOP_KEY+ id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY+ id);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson!=null){
            //返回一个错误信息
            return null;
        }
        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在，返回错误
        if (shop == null) {
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+ id,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+ id, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);

        //Thread.sleep(200);

        //2.封装逻辑过期时间
        RedisData redisData=new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));

        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));

    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if(x==null || y==null){
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //2.计算分页查询
        int from=(current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end=current*SystemConstants.DEFAULT_PAGE_SIZE;

        //3.查询redis，按照距离排序，分页。
        String key=SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoRadiusCommandArgs.newGeoRadiusArgs().includeDistance().limit(end)
        );
        //4.解析出id
        if(results==null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if(list.size()<=from){
            return Result.ok(Collections.emptyList());
        }
        //4.1.截取from~end的部分
        List<Long> ids=new ArrayList<>(list.size());
        Map<String,Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(result->{
            //4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5.根据id查询Shop
        String idStr=StrUtil.join(",",ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
